The rumored Sony “PlayStation Phone”, a PSP-cum-smartphone, has long been the subject of rabid speculation. Last month, amidst purported pics and device specs, those rumors started to feel like they were firming up. Last we looked at the project, it seemed that Sony Ericsson might debut the gaming phone at the Mobile World Congress in February. In the latest addition to this saga, an invitation to a Sony Ericsson France event hints that the phone’s debut might be as soon as December 9.

A snapshot of the invitation unites the geometric icons Sony uses to identify buttons on the PlayStation controller with a phone-handset icon. These sort of teases never say outright what new products is about to be unveiled, but there’s not much wiggle-room for ambiguity here. Whatever Sony Ericsson France has to show off may not be the same hardware we looked at earlier, or the company may not even release any information we haven’t already come across, but it’s hard to argue that something on the cusp of smartphones and PlayStation games isn’t on the menu.

If earlier rumors pan out, the device will be running a next-gen Android release (both 2.3 and 3.0 are up in the air), boast a 1GHz processor, and include 512MB of RAM. The codename “Zeus” has been thrown around for the in-development phone, and whatever the final name becomes, it’s likely to end up under the Sony Ericsson Xperia banner.